Degenhardt T P, Thorpe S R, Baynes J W
Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA.
Cell Mol Biol (Noisy-le-grand). 1998 Nov;44(7):1139-45.
Methylglyoxal is formed in vivo by spontaneous decomposition of triose phosphate intermediates in aerobic glycolysis. It may also be formed during oxidative degradation of both carbohydrates (pentoses and ascorbate) and lipids (arachidonate). In addition to reaction with arginine residues to form imidazolone adducts, methylglyoxal reacts with lysine residues in protein to form N(epsilon)-(carboxyethyl)lysine (CEL) and the imidazolium crosslink, methylglyoxal-lysine dimer (MOLD). Like the glycoxidation products, N(epsilon)-(carboxymethyl)lysine (CML) and glyoxal-lysine dimer (GOLD) which are formed on reaction of glyoxal with protein, CEL and MOLD increase in lens proteins and skin collagen with age. CML and CEL also increase in skin collagen in diabetes, while all four compounds increase in plasma proteins in uremia. Overall, CML, CEL, GOLD and MOLD are quantitatively the major biomarkers of the Maillard reaction in tissue proteins. GOLD and MOLD, in particular, are present at 10-50 fold higher concentrations than the fluorescent crosslink, pentosidine. Together, these dicarbonyl-derived advanced glycation endproducts (AGEs) represent the major chemical modifications that accumulate in tissue proteins with age and in chronic diseases such as diabetes and atherosclerosis.
甲基乙二醛在体内由有氧糖酵解过程中磷酸丙糖中间体的自发分解形成。它也可能在碳水化合物（戊糖和抗坏血酸）和脂质（花生四烯酸）的氧化降解过程中形成。除了与精氨酸残基反应形成咪唑啉酮加合物外，甲基乙二醛还与蛋白质中的赖氨酸残基反应，形成N（ε）-（羧乙基）赖氨酸（CEL）和咪唑鎓交联物甲基乙二醛-赖氨酸二聚体（MOLD）。与乙二醛与蛋白质反应形成的糖氧化产物N（ε）-（羧甲基）赖氨酸（CML）和乙二醛-赖氨酸二聚体（GOLD）一样，CEL和MOLD在晶状体蛋白和皮肤胶原蛋白中会随着年龄的增长而增加。糖尿病患者皮肤胶原蛋白中的CML和CEL也会增加，而在尿毒症患者的血浆蛋白中，这四种化合物都会增加。总体而言，CML、CEL、GOLD和MOLD在数量上是组织蛋白中美拉德反应的主要生物标志物。特别是GOLD和MOLD的浓度比荧光交联物戊糖苷高10至50倍。这些由二羰基衍生的晚期糖基化终产物（AGEs）共同代表了随着年龄增长以及在糖尿病和动脉粥样硬化等慢性疾病中在组织蛋白中积累的主要化学修饰。
